The present invention relates to pressure-fluid supply systems, and in particular, to a system for use in combination with a boom loader device.
Hydraulically controlled boom loaders are widely used in the logging industry and elsewhere. Conventionally, a boom loader includes a mast designed to be secured to the bed of a truck or the like. The mast may have a pair of opposed, hydraulically controlled legs, or outriggers, which are extensible to positions contacting the ground on either side of the truck bed to stabilize the loader. Mounted on the upper end of the mast, for rotation relative thereto, is a platform on which the loader's hydraulically controlled boom and grapple are carried. Typically, the hydraulic equipment carried on the platform includes six units which must be supplied with pressure fluid. These are a motor for controlling the rotational position of the platform; a motor for controlling the rotational position of the grapple; a pair of rams controlling movement of the boom arms; and a pair of rams controlling movement of the grapple arms. In addition, as noted above, the two outriggers on the mast must be separately supplied with pressurized hydraulic fluid.
In the past, a common type of hydraulic fluid supply system used in such a boom loader is one powered by a take-off pump unit connected to the truck's drive system. The pump receives hydraulic fluid from a fluid reservoir contained in the loader's mast, and supplies pressurized hydraulic fluid to the loader's hydraulic units. Pressurized hydraulic fluid is supplied from the pump to a valve on the mast for controlling the two outriggers, and to a valve on a platform, for controlling the (six) hydraulic units carried thereon. Supply of pressurized fluid from the pump to the valve on the relatively rotatable platform, and from such valve back to the reservoir in the mast occurs through a rotary fluid seal interconnecting the mast and the platform.
Two major problems are inherent in the just-described fluid supply system used in conventional boom loaders. First, setting up the loader on the truck requires a number of time-consuming and relatively expensive operations, including attaching the pump to the truck's drive system, and connecting the pump to the various loader fluid ports. Not uncommonly, such set up requires several days and may cost several thousand dollars. Accordingly, once the loader is mounted on, and connected to the truck, economy dictates that it remain there, thus limiting the use of the truck for other purposes.
A second problem concerns the use of a rotary fluid seal to transport hydraulic fluid between the stationary mast and the relatively rotatable loader platform. Such seals are expensive, bulky, and relatively difficult to maintain.
A general object of the present invention to provide, for use with a truck-mounted boom loader device, a fluid supply system which overcomes the above-mentioned problems encountered in the prior art.
More specifically, it is an object of the present invention to provide such a fluid supply system which operates independently of the drive system of a truck on which the loader device is mounted.
Yet another object of the present invention is to provide such fluid supply system which obviates the need for a rotary seal between a loader's mast and rotatable platform.
Another related object of the present invention is to provide a boom loader which can be mounted and dismounted readily from the bed of a truck or the like.
The present invention includes a pressure-fluid supply system for use in combination with a pair of relatively rotatable structures, where one structure is intended to carry fluid-operated equipment to be operated by the system. The system includes a pump unit having a stator portion anchored on one of the relatively rotatable structures, and a power-input rotor rotatably mounted thereon. Also included in the system is a power-operated prime mower including a stator portion anchored to the other of the two relatively rotatable structures, and a power-output rotor rotatably mounted thereon. The power-output rotor is drivingly coupled to the pump's rotor, about the axis of rotation of the one structure, relative to the other, wherein the one structure may be rotated endlessly during pump operation.
In a preferred embodiment of the invention, the two rotatable structures are the mast and platform of a loader device, with fluid-operated equipment being carried on the platform. The system includes a fluid reservoir which is mounted on the platform for rotation therewith. The pump is connected to the equipment and to the reservoir, forming therewith, a self-contained fluid supply and exhaust apparatus.